Piston rings



March 12, 1963 K. NISPER PISTON RINGS Filed June 12, 1958 INVENTOR. I

Kenneth J. N/sper F lg. 3 BY A TTORNEYS United States Patent O 3,081,100 PISTON RINGS Kenneth Nisper, Muskegon, Mich, assignor to Muskegon Piston Ring Company, Muskegon, Mich., a corporation of Michigan Filed June 12, 1958, Ser. No. 741,606

6 Claims. (Cl. 277-140) This invention relates to piston rings of the three component type having a pair of parted rails and a parted, resilient spacer-expander for supporting the rails. More particularly, this invention is directed to the construction of the spacer-expander.

In the design and manufacture of automotive engines, a wide variety of design requirements are encountered in the piston ring field. These involve a variety of degrees of flexibility of the ring and a wide variety in the depth of the ring groove. These various design requirements have frequently confronted ring design personnel with conflicting physical and performance requirements. Heretofore, where the ring groove was deepened, it was necessary to increase correspondingly the radial depth of the ring to prevent excessive necklacing. As a result, the ring became less flexible and lacked essential operational characteristics.

This invention resolves this problem by a novel strucmm which divorces the depth of the rails from the depth of the spacer-expander. spacer-expander may be varied to match the depth of the ring groove involved without varying the radial depth of the rails. A piston ring may be constructed with this invention having a substantial radial depth to meet the requirements of a deep ring groove yet, utilize rails of narrow radial depth characterized by a high degree of flexibility. This is particularly advantageous in providing a piston ring having highly efficient operating characteristics and at the same time adapted to easy installation. Further, this variation in the depth of the ring may be made without changing the fundamental design of the spacer-expander. In fact, it may be accomplished either by changing only one simple die of the several dies required to form the spacer-expander blank or by utilizing a stock material of a different width or both. Thus, the cost of adapting the ring is reduced to a minimum.

This invention provides a spacer-expander characterized by a high degree of flexibility. The location of the bight or web portion of the structure as separated sections on the outer radial periphery connected only by the portions of the structure at the radial inner periphery creates a highly flexible structure. This flexibility is further increased by the rounded shape of the connecting portions at the inner radial periphery. This'flexibility assures an even distribution of radial thrust against the rails throughout their circumference. This result has been accomplished without loss of the radial tension necessary to effect proper sealing against the cylinder walls.

The ring has an added advantage of being characterized by a high degree of openness. That is, of the total area of the spacer-expander, a larger proportion of it is open as compared with more conventional designs. This substantially improves its operational characteristics by reducing its tendency to clog with carbon deposits. The more open the ring, the longer its efficient operating life.

These and other objects and purposes of this invention will be immediately understood by those acquainted with the design, manufacture and use of piston rings upon reading the following specification and the accompanying drawings.

In the drawings:

FIG. 1 is a fragmentary view of a strip of stock illus- Thus, the radial depth of the spacer-expander.

FIG. 4 is a fragmentary sectional elevation view of the spacer-expander installed in the ring groove of a piston.

In executing the objects and purposes of this invention, a piston ring is provided having a pair of parted rails and a parted, resilient expander-spacer. The expander-spacer is formed from a ribbon of suitable material and consists of a plurality of annuli arranged in tandem and joined along the center axis of the ribbon by small connecting webs. The annuli are elongated transversely of the ribbon or blank and their ends are rounded. The connecting webs space the annuli longitudinally of the blank. Each web has a pair of laterally extending tongues, one on each side. The tongues are laterally aligned and are equi-dist-ant from the adjacent annuli. The blank is bentin a cross sectional U-shape with the connecting webs centered in the bight of the U at the radial outer periphery of the spacer. The tongues extend radially inwardly and have their free ends turned axially outwardly from the spacer to form pads or stops for the rails.

Referring specifically to the drawings, the numeral 1 indicates a stock material of ribbon-like form such as a spring steel or other materal having suitable resilient characteristics (FIG. 1). To form the spacer-expander of this invention, the stock 1 is provided with slits 2. The slits are arranged in groups of four, two in closely spaced, parallel relationship on each side of the stock. The slits 2 are aligned in pairs on opposite sides of the stock and terminate short of the centerline of the stock, leaving a narrow web 3 along this centerline. The slits 2 also form a pair of laterally projecting tongues 4, each integral at its base with the web 3 and extending outwardly to the margin of the stock.

Between the groups of slits 2 lengthwise of the stock 1, rectangular blocks remain which are next provided with an aperture 5. The apertures 5 are elongated transversely of the stock and have rounded ends. The edge margins of the blocks are then trimmed to generally parallel the walls of the apertures 5. This operation forms the ends or outer side portions of the blocks into rounded loops 6 and the structure of the spacer between the connecting webs 3 into elongated annuli 7. A substantial portion of the laterally extending sides of the annuli 7 are straight and parallel.

It will be recognized that the foregoing description of cutting the spacer-expander blank sets forth only one of the several ways in which this can be accomplished. Other methods of forming the blank may be employed. Also, the order of performing each of the particular steps involved may be varied.

The ends of the tongues 4 are each bent sharply to the plane of the blank to form tan-gs or tabs 10. This bend is slightly less than so they will have a slight incline-- tion in the finished spacer-expander. The purpose of this will be explained later.

The blank is then bent into a U-shaped cross sectional configuration along two lines 11 and 11a. The lines 11 and 11a parallel the centerline of the stock '1. The Ibending along these lines is done in such fashion that when the spacer has been formed to its final shape, the tabs 10 extend outwardly from the spacer-expander.

After forming into the U-shape, the outer side portions or loops 6 become the railseats 12 .and 12a (FIG. 3). These are parallel and spaced apart a suflicient distance to support the rails properly within the ring groove. When the blank is coiled into the finished spacer, the loops 6 extend toward the radially inner edge of the spacer-expander. The center portions of the annuli 7 together with the connecting webs 3 serve as a bight portion 13 of the spacer-expander and are located along its radial outer periphery.

It will be noted that the spacer-expander alternately has continuity of structure on opposite radial edges. Along the radial outer periphery this is accomplished by the circumferentially spaced webs 3 and along the radial inner periphery by the circumferentially spaced loops 6. This creates a highly flexible structure yet one capable of producing substantial radial tension.

In the completed piston ring, both rails 18 and the spacer-expander are parted at 25 (FIG. 2). This parting in the rails is closed or substantially closed when the piston ring is installed. This parting is closed in the installed spacer-expander and its ends butt. This is necessary to create radial tension in the spacer so it will urge the rails 18 against the cylinder walls.

It will be noted that piston rings utilizing spacer-expande-rs of this invention have a high degree of openness. Substantially the entire radial outer wall or bight portion 13 of the structure is open, together with a major portion of the rail seats 12 and 12a. This greatly reduces the accumulation of carbon deposit on the ring with a corresponding increase in the effective life of the piston ring. The openness of the rail seats reduces friction between the rails and the seats. The rails, thus, have greater freedom of movement for following the contour of the cylinder walls. This design permits this high degree of openness to be accomplished without sacrifice of essential strength and body structure adequate to develop the required radial tension and to properly support and space the rails.

The position of the tangs or pads 10 with respect to the inner and outer radial peripheries of the spacer will depend upon the length of the tongues 4. In the blank illustrated in FIG. 1, the length of the tongues 4 is determined by the width of the stock. However, a suitable die may be used to trim the ends ofythe tongues, thus shortening them. This will have the efiect of relocating the pads 10 radially outwardly and between the inner andouter margins of the spacer-expander. Such a spacer-expander will accommodate rails 18 of narrower radial dimension.

Thus, simply by varying the length of the tongues 4 and correspondingly adjusting the position of [the bends forming the pads10, this spacer-expander can be adapted to a wide range ofrail widths without changing the basic structure of the spacer or its flexibility or resiliency characteristics. These characteristics are very important to the eflicient operation-of this type of piston ring. The tooling changes necessary to do this are comparatively simple and inexpensive. This invention divorces the structure controlling the operating characteristics of the spacerexpander from the structure determining the rail width.

The pads 10 may be bent to a position normal to the plane of the rail seats 12 and 12a. However, they are preferably inclined at a slight angle, as previously described and illustrated in FIG. 4. With the pads 10 so inclined, their engagement upon the inner radial edge of the rails 18 will, by reason of the tension of the ring, cause the rails to be forced sideways against the walls 21 and22 of the ring groove 23 as well as outwardly against the cylinder wall 26. This creates what is known as wedging action, improving the side sealing action of the rails in the ring groove. While this inclination of the pads 10 is shown and described, it is not a part of this invention.

It will be seen that this invention provides a particularly inexpensive, flexible and adaptable spacer-expander for use in three piece piston rings. It is particularly economical to adapt from one ring groove depth to another. 'Further, this may be done without changing the radial depth of the rails and thus the flexibility of the ring as a whole. This spacer-expander is particularly adapted to mass production since it may be completely formed as a fiat ribbon and then passed continuously through suitable equipment to bend it to the U-shaped cross sectional configuration and coiled to ring shape. This reduces the complexity of its manufacture and permits its manufacturing costs to be held to a minimum.

It will be recognized that various modifications of this invention may be made, each within the principles of the invention. Such modifications are to be considered as included in the hereinafter appended claims, unless these claims, by their language, expressly state otherwise.

I claim:

1. A spacer expander for a piston ring comprising: a plurality of annuli spaced from each other; a web adjacent to each annulus and joining said annuli one to the other; said annuli being bent along two parallel lines extending longitudinally of said spacer expander one on each side of said webs whereby said spacer expander has a generally U-shaped cross sectional configuration and outer end portions of said annuli form spaced parallel rail seats; said spacer expander being circular with said webs on the radial outer periphery thereof; tongue-like rail stops projecting from the sides of certain of said webs; portions of said rail stops being bent along the same lines as said annuli and lying in the same plane as said rail seats; the ends of said rail stops projecting outwardly from the faces of said rail seats and adapted to serve as rail engaging pads.

2. A spacer expander for a piston ring comprising: a plurality of annuli spaced from each other; a web adjacent each annulus and joining said annuli one to the other; said annuli being bent along two parallel lines extending longitudinally of said spacer expander one on each side of said webs whereby said spacer expander has a generally U-shaped cross sectional configuration and outer end portions of said annuli form. spaced parallel rail seats; said spacer exander being circular with said webs on the radial outer periphery thereof; tongue-like rail stops projecting from opposite sides of certain of said webs; portions of said rail stops being bent along the same lines as said annuli and lying in the same plane as said rail seats; the ends ofsaid rail stops projecting outwardly from the faces of said rail seats and adapted to serve as rail engaging pads.

3. -A spacer expander for a piston ring comprising: a plurality of annuli spaced from each other; a web adjacent each annulus and joining said annuli one to the other; said annuli being bent along two parallel lines extending longitudinally of said spacer expander one on each side of said webs whereby said spacer expander has a generally U-shaped cross sectional configuration and outer end portions of said annuli form spaced parallel rail seats; said spacer expander being circular with said webs on the radial outer periphery thereof; tongue-like rail stops projecting from opposite sides of each of said webs; portions of said rail stops being bent along the same lines as said annuli and lying in the same plane as said rail seats; the ends of said rail stops projecting outwardly from the faces of said rail seats and adapted to serve as rail engaging pads.

4. A spacer expander for a piston ring, said spacer expander having a U-shaped cross sectional configuration with the bight portion of said U at the outer radial periphery of said spacer expander; the legs of said U forming parallel circumferentially spaced rail seats each of an open loop shape; connecting webs along the median line of said bight portion joining said rail seats one'to the other; tongue-like rail stops integral with said webs and extending from each side thereof; said rail stops lying in the plane of both the bight and leg portions of said U; the ends of said rail stops being bent outwardly from the faces of said rail seats and adapted to serve as rail engaging pads.

5. A spalcer expander as described in claim 4 wherein said connecting webs are spaced apart circumferential-1y of said spacer expander and are joined only by the loop shape-d rail seats at the inner radial periphery of said spacer expander.

6. A spacer expander for a piston ring, said spacer expander having a U-shaped cross sectional configuration with the bight porition of said U at the outer radial periphery of said spacer expander; the legs of said U forming parallel circumferential ly spa/ced rail seats each of an open loop shape; connecting webs along the median line of said bight portion joining said rail seats one to the other; tongue-like rail stops integral with certain of said webs and extending therefrom in the plane of both the bight and leg portions of said U; the ends of said rail stops being bent outwardly from the faces of said rail seats and adapted to serve as rail engaging pads.

References Cited in the file of this patent UNITED STATES PATENTS Burns Mar. 18, 1958 

1. A SPACER EXPANDER FOR A PISTON RING COMPRISING: A PLURALITY OF ANNULI SPACED FROM EACH OTHER; A WEB ADJACENT TO EACH ANNULUS AND JOINING SAID ANNULI ONE TO THE OTHER; SAID ANNULI BEING BENT ALONG TWO PARALLEL LINES EXTENDING LONGITUDINALLY OF SAID SPACER EXPANDER ONE ON EACH SIDE OF SAID WEBS WHEREBY SAID SPACER EXPANDER HAS A GENERALLY U-SHAPED CROSS SECTIONAL CONFIGURATION AND OUTER END PORTIONS OF SAID ANNULI FORM SPACED PARALLEL RAIL SEATS; SAID SPACER EXPANDER BEING CIRCULAR WITH SAID WEBS ON THE RADIAL OUTER PERIPHERY THEREOF; TONGUE-LIKE RAIL STOPS PROJECTING FROM THE SIDES OF CERTAIN OF SAID WEBS; PORTIONS OF SAID RAIL STOPS BEING BENT ALONG THE SAME LINES AS SAID ANNULI AND LYING IN THE SAME PLANE AS SAID RAIL SEATS; THE ENDS OF SAID RAIL STOPS PROJECTING OUTWARDLY FROM THE FACES OF SAID RAIL SEATS AND ADAPTED TO SERVE AS RAIL ENGAGING PADS. 